Why a 5 day duration is used for BOD determination?

Why a 5 day duration is used for BOD determination?

The standard oxidation (or incubation) test period for BOD is 5 days at 20 degrees Celsius (°C) (BOD5). The BOD5 value has been used and reported for many applications, most commonly to indicate the effects of sewage and other organic wastes on dissolved oxygen in surface waters (see TECHNICAL NOTE).

Why is BOD test done at 20 degrees Celsius?

Since cold water will hold more dissolved air, aerating cold dilution water will give a higher oxygen content than if the dilution water was aerated at 20 C. After placing the samples in an incubator at 20 C, the water will warm and not be able to hold as much DO. As a result, bubbles may form in the bottles.

What is the five day BOD of the waste?

For a waste, the 5-day BOD at 20° C is 180 mg/l.

Why do we measure BOD and COD of a sample?

Analytical tests aimed at establishing the concentration (typically in mg/L or ppm) of organic (i.e., carbon-containing) matter have traditionally been used to determine the relative “strength” of a wastewater sample.

Why is BOD testing completed at a wastewater treatment plant?

BOD is the traditional, most widely used test to establish concentration of organic matter in wastewater samples (i.e., relative strength). The change in DO concentration over five days represents the “oxygen demand” for respiration by the aerobic biological microorganisms in the sample.

What is the importance of measuring BOD of a water body?

The BOD is an important parameter for assessing water quality. It deals with the amount of oxygen consumption (mg O2 L− 1) by aerobic biological organisms to oxidize organic compounds. Sewage with high BOD can cause a decrease in oxygen of receiving waters, which in turn can cause the death of some organism.

What is measured by BOD?

BOD is a measure of the amount of oxygen required to remove waste organic matter from water in the process of decomposition by aerobic bacteria (those bacteria that live only in an environment containing oxygen).

Why is BOD measured?

Biochemical oxygen demand (BOD) represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature. The decay of organic matter in water is measured as biochemical or chemical oxygen demand.

What is the importance of BOD test in sewage analysis?

BOD finds its primary importance in sewage treatment plants. It gives the respiration rate of sewage, sludge, soil, garbage. It determines the rate of respiration in living beings. Measuring BOD gives the COD or Chemical Oxygen Demand of inorganic substances.

What is the BOD value of sample at 5 days?

* Generally as per global standards BOD value of sample at 5 days which incubated at 20 degrees Celsius is represented as the standard BOD of the sample. The reason for taking 5 days BOD as standard is due to the following fact: The “Dissolved Oxygen” present in water gets used for the decomposition of organic matter as well as nitrogenous matter.

Why is 5 days BOD the standard BOD for decomposition?

The reason for taking 5 days BOD as standard is due to the following fact: The “Dissolved Oxygen” present in water gets used for the decomposition of organic matter as well as nitrogenous matter. From the combined BOD curve, we have two oxygen demands: 1. Carbonaceous BOD (initial), 2.

What is the BOD 5 value?

The standard oxidation (or incubation) test period for BOD is 5 days at 20 degrees Celsius (°C) (BOD 5). The BOD 5value has been used and reported for many applications, most commonly to indicate the effects of sewage and other organic wastes on dissolved oxygen in surface waters (see TECHNICAL NOTE).

How do you measure BOD value?

In Laboratory, The BOD value is measured by measuring the difference of dissolved oxygen (DO) of the sample after 5 days of incubation at 20 degrees centigrade. The answer to this question is among the basic building blocks of Environmental Engineering, Yet…